Wave propagation in a solar quiet region and the influence of the magnetic canopy

Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, 15236 Penteli, Greece
e-mail: jkonto@noa.gr; georgia@noa.gr; kostas@noa.gr

Received: 24 July 2015
Accepted: 20 November 2015

Abstract

Aims. We seek indications or evidence of transmission/conversion of magnetoacoustic waves at the magnetic canopy, as a result of its impact on the properties of the wave field of the photosphere and chromosphere.

Methods. We use cross-wavelet analysis to measure phase differences between intensity and Doppler signal oscillations in the Hα, Ca ii h, and G-band. We use the height of the magnetic canopy to create appropriate masks to separate internetwork (IN) and magnetic canopy regions. We study wave propagation and differences between these two regions.

Results. The magnetic canopy affects wave propagation by lowering the phase differences of progressive waves and allowing the propagation of waves with frequencies lower than the acoustic cut-off. We also find indications in the Doppler signals of Hα of a response to the acoustic waves at the IN, observed in the Ca ii h line. This response is affected by the presence of the magnetic canopy.

Conclusions. Phase difference analysis indicates the existence of a complicated wave field in the quiet Sun, which is composed of a mixture of progressive and standing waves. There are clear imprints of mode conversion and transmission due to the interaction between the p-modes and small-scale magnetic fields of the network and internetwork.